This invention relates to a liquid jet unit used in an industrial machine, such as a manufacturing machine for manufacturing optical filters, and an image recording apparatus such as a plotter and a printer, and a piezoelectric vibrator unit used in the liquid jet unit. This invention also relates to methods of manufacturing the liquid jet unit and the piezoelectric vibrator unit.
Industrial machines such as manufacturing machines and image recording apparatuses such as plotters and printers are available, which employ a liquid jet head for ejecting liquid in the form of liquid droplets. For example, an industrial machine for manufacturing an optical filter is designed to eject color material in the form of liquid droplets onto a filter substrate using an ejection head (a kind of liquid jet head). An image recording apparatus is designed to eject ink droplets from a recording head (a kind of liquid jet head) onto a printing or recording medium such as paper.
These industrial machines and image recorders require high accuracy for the amount and speed of the ejected liquid droplets. For example, the optical filter manufacturing machine must eject a proper amount (i.e. a proper ejection amount) of an color material droplet onto a proper position with high accuracy since the optical filter manufactured with the industrial machine is used with a liquid crystal display, etc. The image recording apparatus requires high accuracy as to a position onto which an ink droplet is ejected, and an amount of the ejected ink, in order to improve image quality and speed up the recording.
The liquid jet head, widely used in these industrial machines and image recording apparatuses, typically includes: a flow passage unit formed with a plurality of ink flow passages each extending from a reservoir through a pressure chamber to a nozzle opening; and a piezoelectric vibrator unit being placed on the rear of the flow passage unit and having a plurality of piezoelectric vibrators provided in a one-to-one correspondence with the pressure chambers for changing the volumes of the corresponding pressure chambers. The liquid jet head ejects liquid from a nozzle opening by changing the volume of the corresponding pressure chamber using deformation (displacement) of the corresponding piezoelectric vibrator.
The piezoelectric vibrator unit is manufactured, for example, according to the following procedure: First, common internal electrodes and segment internal electrodes are laminated alternately with a piezoelectric material interposed between adjacent internal electrodes to manufacture a plate-like laminated substrate, and a common external electrode electrically conducted to the common internal electrodes and a segment external electrodes electrically conducted to the segment internal electrodes are formed on the surface of the laminated substrate to obtain a laminated member. After the base end side portion of the laminated member is fixed to a fixing plate, the leading end side portion of the laminated member is cut into a plurality of segments (piezoelectric vibrators) each having an extremely narrow width of about 50 xcexcm to 100 xcexcm using a wire saw, a dicing saw, etc.
The piezoelectric vibrator unit thus manufactured is disposed in a state in which the displaceable surfaces of piezoelectric vibrators are contacted with diaphragm parts for the pressure chambers, respectively.
Another type of the liquid jet head has piezoelectric vibrators that are provided in the diaphragm parts for the pressure chambers, respectively. The liquid jet head of this type ejects liquid from a nozzle opening by changing the volume of the corresponding pressure chamber using deformation (displacement) of the corresponding piezoelectric vibrator similarly.
The liquid jet head using the piezoelectric vibrator unit has an advantage in that piezoelectric vibrators having identical displacement characteristic can be easily obtained because the piezoelectric vibration unit is manufactured such that the laminated member is cut to provide the piezoelectric vibrators. Namely, a come-like piezoelectric vibrator is provided by cutting substantially the same piezoelectric vibrator unit. Therefore, since it is substantially the same one first, the variation in the characteristic between each piezoelectric vibrator is small. However, each piezoelectric vibrator obtained as a consequence of cutting has an extremely narrow width, and therefore slight variation in width may occur. Since the piezoelectric vibrator is of laminated type, if a pinhole larger than the width of the piezoelectric vibrator exists in the internal electrode, the internal electrode is brought partially out of electric conduction by the presence of the pinhole. In the case of the industrial machine of which especially high precision is required, even if it is the small piezoelectric vibrator of variation, the small highly precise characteristic of variation is demanded more than it. Thus, the width variation of the piezoelectric vibrators, the defect of the internal electrode, and the like cause the piezoelectric vibrators to have sight varied displacement amounts.
In the case of the liquid jet head in which the piezoelectric vibrators are provided in the diaphragm parts for the pressure chambers, the thickness, shape, etc., of piezoelectric material is likely to be varied, and thus the displacement amounts of the piezoelectric vibrators are varied largely in comparison to the case where the piezoelectric vibrators constitute the piezoelectric vibrator unit.
Such displacement amount variation of the piezoelectric vibrators adversely affect the liquid ejection characteristic of the liquid jet head and thus is not preferable. For example, in the case of the optical filter manufacturing machine, the sizes of pixels forming the optical filter are varied depending on the respective nozzle openings, and in the case of the image recording apparatus, the pixels deposited onto a recording medium are made non-uniform in size.
Further, the liquid ejection characteristic of the liquid jet head is also changed due to the attachment state of the vibrator unit to the flow passage unit and the shape of the ink flow passage in the flow passage unit.
To prevent these problems, it is conceivable to fill one scanning line with liquid droplets ejected from a plurality of nozzle openings, but this will lower the throughput since the liquid jet head needs to be scanned plural times to fill one scanning line.
This is particularly not preferable for the industrial machines since the lowered throughput results in lowered production efficiency and thus increased cost of the product.
The present invention was made in order to solve the above-mentioned problems, and an object of the present invention is to make uniform the displacement amounts of piezoelectric vibrators, and to thereby make uniform the liquid ejection characteristic of a liquid jet head.
According to the present invention, one or more of piezoelectric vibrators, which will cause variation in liquid ejection characteristic, is subjected to a displacement amount adjustment treatment to make uniform the displacement amounts of piezoelectric vibrators.
The present invention provides the followings:
(1) A manufacturing method of manufacturing a piezoelectric vibrator unit comprising a plurality of piezoelectric vibrators, each having, at least in part, a laminate structure of electrodes and at least one layer of piezoelectric material, said manufacturing method comprising:
a displacement amount measurement step of measuring a displacement amount of each of the piezoelectric vibrators with respect to a reference voltage; and
a displacement amount adjustment step of setting a treatment condition for at least one of the piezoelectric vibrators based on a result of measurement by the displacement amount measurement step, and subjecting the at least one of the piezoelectric vibrators to a displacement amount adjustment based on the thus set treatment condition, thereby making the displacement amounts of the piezoelectric vibrators uniform.
(2) The manufacturing method of (1), wherein:
the laminate structure includes an external electrode as an outermost one of the electrodes in a laminate direction, and an internal electrode that is to be different in polarity from the external electrode and that is confronted with the external electrode through a layer of the piezoelectric material to form an active region,
the displacement amount adjustment includes a step of trimming a portion of the external electrode of the at least one piezoelectric vibrator, the portion being located within the active region.
(3) The manufacturing method of (2), wherein the displacement amount adjustment step includes setting a piezoelectric vibrator having the smallest displacement amount with respect to the reference voltage as a reference vibrator, and adjusting the displacement amounts of the piezoelectric vibrators, other than the reference vibrator, to be identical to the displacement amount of the reference vibrator.
(4) The manufacturing method of (2), wherein said displacement amount adjustment step includes setting a piezoelectric vibrator having the smallest displacement amount with respect to the reference voltage as a reference vibrator, and adjusting the displacement amounts of all the piezoelectric vibrators to be identical to a target displacement amount smaller than the displacement amount of the reference vibrator.
(5) The manufacturing method of any one of (2) to (4), wherein the step of trimming includes trimming the portion of the external electrode using laser beam.
(6) The manufacturing method of any one of (2) to (5), further comprising:
laminating piezoelectric material layers and internal electrode layers alternately to provide a laminate substrate;
forming an external electrode layer on at least a surface of the laminate substrate to provide a laminate member; and
at least partially cutting the laminate member to provide the piezoelectric vibrators in the form of teeth of comb.
(7) The manufacturing method of (1), further comprising
a semi-saturation polarization treatment step, executed prior to the displacement amount measurement step, of polarizing the piezoelectric material to put the piezoelectric material into a semi-saturation polarization state, not into a saturation polarization state, and wherein
the displacement amount adjustment includes a re-polarization treatment step of re-polarizing the piezoelectric material of the at least one piezoelectric vibrator in a direction from the semi-saturation polarization state toward the saturation polarization state.
(8) The manufacturing method of (7), wherein the displacement amount adjustment step includes setting a piezoelectric vibrator having the largest displacement amount with respect to the reference voltage as a reference vibrator, and adjusting the displacement amounts of the piezoelectric vibrators, other than the reference vibrator, to be identical to the displacement amount of the reference vibrator.
(9) The manufacturing method of (7), wherein the displacement amount adjustment step includes setting a piezoelectric vibrator having the largest displacement amount with respect to the reference voltage as a reference vibrator, and adjusting the displacement amounts of all the piezoelectric vibrators to be identical to a target displacement amount larger than the displacement amount of the reference vibrator.
(10) The manufacturing method of any one of (7) to (9), wherein the semi-saturation polarization state is set to be 90% of the saturation polarization state.
(11) The manufacturing method of any one of (7) to (10), wherein at least one of the semi-saturation polarization treatment step and the re-polarization treatment step uses a voltage value applied to the piezoelectric material as a variable, and adjusts the voltage value to obtain a desired degree of polarization.
(12) The manufacturing method of any one of (7) to (11), wherein at least one of the semi-saturation polarization treatment step and the re-polarization treatment step uses a time period, for which a voltage is applied to the piezoelectric material, as a variable, and adjusts the time period to obtain a desired degree of polarization.
(13) The manufacturing method of any one of (7) to (12), wherein at least one of the semi-saturation polarization treatment step and the re-polarization treatment step uses a temperature of the piezoelectric material as a variable, and adjusts the temperature to obtain a desired degree of polarization.
(14) The manufacturing method of (1), further comprising:
a saturation polarization treatment step, executed prior to the displacement amount measurement step, of polarizing the piezoelectric material to put the piezoelectric material into a saturation polarization state,
wherein the displacement amount adjustment includes a spot heating treatment step of locally heating the piezoelectric material of the at least one piezoelectric vibrator in a direction away from the saturation polarization state.
(15) The manufacturing method of (14), wherein the displacement amount adjustment step includes setting a piezoelectric vibrator having the smallest displacement amount with respect to the reference voltage as a reference vibrator, and adjusting the displacement amounts of the piezoelectric vibrators, other than the reference vibrator, to be identical to the displacement amount of the reference vibrator.
(16) The manufacturing method of (14), wherein the displacement amount adjustment step includes setting a piezoelectric vibrator having the smallest displacement amount with respect to the reference voltage as a reference vibrator, and adjusting the displacement amounts of all the piezoelectric vibrators to be identical to a target displacement amount smaller than the displacement amount of the reference vibrator.
(17) The manufacturing method of any one of (14) to (16), wherein the spot heating treatment step includes heating the piezoelectric material to a Curie temperature of the piezoelectric material or higher.
(18) The manufacturing method of anyone of (14) to (17), wherein the spot heating treatment step includes locally applying a laser beam to the piezoelectric material of the at least one piezoelectric vibrator.
(19) The manufacturing method of any one of (14) to (17), wherein the spot heating treatment step includes locally applying an infrared ray to the piezoelectric material of the at least one piezoelectric vibrator.
(20) The manufacturing method of any one of (14) to (17), wherein the spot heating treatment step includes locally abutting a heating terminal against the piezoelectric material of the at least one piezoelectric vibrator.
(21) The manufacturing method of (1), further comprising:
a semi-saturation polarization treatment step, executed prior to the displacement amount measurement step, of polarizing the piezoelectric material to put the piezoelectric material into a semi-saturation polarization state, not into a saturation polarization state, and wherein
the displacement amount adjustment step includes a polarization adjustment step of adjusting the polarization state of the piezoelectric material of the at least one piezoelectric vibrator by selecting at least one of a re-polarization treatment of re-polarizing the piezoelectric material in a direction from the semi-saturation polarization state toward the saturation polarization state and a spot heating treatment of locally heating the piezoelectric material to partially depolarizing the piezoelectric material.
(22) The manufacturing method of (1), wherein the displacement amount adjustment includes a heating polarization adjustment step of supplying a polarization drive signal to the electrodes to charging and discharging the piezoelectric material alternately and to generate heat from the at least one piezoelectric vibrator, and polarizing the piezoelectric material of the at least one piezoelectric vibrator under the heat thus generated.
(23) The manufacturing method of any one of (7) to (22), wherein the laminate structure includes common internal electrodes and segment internal electrodes laminated alternately with a layer of the piezoelectric material interposed between adjacent pair of the common and segment internal electrodes to form an active region in a free end part.
(24) The manufacturing method of (23), wherein each of the piezoelectric vibrators is displaced in a direction orthogonal to a lamination direction by the action of an electric field.
(25) The manufacturing method of (23), wherein each of the piezoelectric vibrators is displaced in a lamination direction by the action of an electric field.
(26) The manufacturing method of any one of (23) to (25), further comprising:
laminating piezoelectric material layers and internal electrode layers alternately to provide a laminate substrate;
forming an external electrode layer on at least a surface of the laminate substrate to provide a laminate member; and
at least partially cutting the laminate member to provide the piezoelectric vibrators in the form of teeth of comb.
(27) A manufacturing method of manufacturing a liquid jet head comprising a plurality of piezoelectric vibrators, each having, at least in part, a laminate structure of electrodes and at least one layer of piezoelectric material, and a plurality of liquid flow passages respectively formed for communication from a reservoir through pressure chambers to nozzle openings associated with the piezoelectric vibrators, wherein deformation of a piezoelectric vibrator causes deformation of a respective pressure chamber and changes liquid pressure in the respective pressure chamber to thereby eject liquid from a respective nozzle opening, the manufacturing method comprising:
an ejection characteristic measurement step of applying the same drive signal to all the piezoelectric vibrators to eject liquid from the nozzle openings, and measuring liquid ejection characteristic in one-by-one basis of the nozzle openings; and
an ejection characteristic adjustment step of setting a treatment condition for at least one of the piezoelectric vibrators based on a result of measurement by the ejection characteristic measurement step, and subjecting the at least one piezoelectric vibrator to a displacement amount adjustment based on the thus set treatment condition, thereby making the liquid ejection characteristic associated with the nozzle openings uniform.
(28) The manufacturing method of (27), wherein the liquid ejection characteristic includes a liquid ejection amount.
(29) The manufacturing method of (27), wherein the liquid ejection characteristic includes a liquid ejection speed.
(30) The manufacturing method of (27), wherein the liquid ejection characteristic includes an area of ejected liquid on an object.
(31) A piezoelectric vibrator unit comprising a plurality of piezoelectric vibrators, each having at least in part, a laminate structure including first and second internal electrodes laminated alternately with a layer of piezoelectric material interposed between adjacent pairs of the first and second internal electrodes to an active region in a free end part, a first external electrode electrically conducted to the first internal electrodes and a second external electrode electrically conducted to the second internal electrodes, wherein a potential difference is given to the piezoelectric material in the active region through the first and second external electrodes to activate the piezoelectric material, thereby displacing the free end part in a direction orthogonal to a lamination direction, wherein:
at least one of the first and second external electrodes is formed on a free end part surface of an outermost layer of the piezoelectric material in the lamination direction so that a part of the piezoelectric material outermost layer, located in the active region, can be activated;
the part of the piezoelectric material outermost layer, located in the active region, is used as a trimming portion whose effective range can be varied by trimming;
an active range of the piezoelectric material outermost layer can be varied by trimming the trimming portion to adjust the displacement amount of the piezoelectric vibrator.
(32) The piezoelectric vibrator unit of (31), wherein the piezoelectric vibrators are manufactured by
laminating piezoelectric material layers and internal electrode layers alternately to provide a laminate substrate;
forming an external electrode layer on at least a surface of the laminate substrate to provide a laminate member; and
at least partially cutting the laminate member to provide the piezoelectric vibrators in the form of teeth of comb.
(33) The piezoelectric vibrator unit of (31) or (32), wherein:
the first internal electrodes are common internal electrodes set to the same potential level for all the piezoelectric vibrators;
the second internal electrodes are segment internal electrodes whose potential level is set depending on the respective piezoelectric vibrator;
the first external electrodes are common external electrodes set to the same potential level for all the piezoelectric vibrators; and
the second external electrodes are segment external electrodes whose potential level is set depending on the respective piezoelectric vibrator.
(34) The piezoelectric vibrator unit of anyone of (31) to (33), wherein each of the piezoelectric vibrators includes an inactive part which is not displaced even when the piezoelectric material in the active region is activated, and the inactive part is joined to a fixing plate.
(35) The piezoelectric vibrator unit of any one of (31) to (34), wherein each of the piezoelectric vibrators includes an inactive part which is not displaced even when the piezoelectric material in the active region is activated, and the first and second external electrodes are brought into electrically conducted to a wiring member in the inactive part.
(36) The piezoelectric vibrator unit of anyone of (31) to (35), wherein the piezoelectric material outermost layer is thicker than an internal layer of piezoelectric material.
(37) A liquid jet head comprising:
a piezoelectric vibrator unit manufactured according to the manufacturing method of any one of (1) to (26); and
a flow passage unit having a plurality of liquid flow passages that are respectively associated with the piezoelectric vibrators, and that respectively extend from a reservoir through pressure chambers to nozzle openings, wherein:
the piezoelectric vibrator unit is attached to the flow passage unit so that the piezoelectric vibrators are respectively contacted with diaphragm parts of the pressure chambers associated with the piezoelectric vibrators; and
deformation of the piezoelectric vibrator deforms the associated pressure chamber and changes liquid pressure to in the associated pressure chamber to thereby eject liquid from the associated nozzle opening.
(38) A liquid jet head manufactured according to the manufacturing method of any one of (27) to (30), the liquid jet head comprising:
a case defining a storage space in which the piezoelectric vibrators can be stored;
an adjustment opening formed through the case for communication between an outside of the case and the storage space to enable access to the piezoelectric vibrators stored in the storage space, wherein
displacement amount adjustment can be conducted to each of the piezoelectric vibrator from the outside of the case through the adjustment opening.
(39) The liquid jet head of (38), wherein each of the piezoelectric vibrator includes common internal electrodes and segment internal electrodes laminated alternately with a layer of the piezoelectric material interposed between adjacent pair of the common and segment internal electrodes to form an active region in a free end part.
(40) The liquid jet head of (39), wherein each of the piezoelectric vibrators is displaced in a direction orthogonal to a lamination direction by the action of an electric field.
(41) The liquid jet head of (39), wherein each of the piezoelectric vibrators is displaced in a lamination direction by the action of an electric field.
(42) The liquid jet head of any one of (39) to (41), wherein the piezoelectric vibrators are manufactured by:
laminating piezoelectric material layers and internal electrode layers alternately to provide a laminate substrate;
forming an external electrode layer on at least a surface of the laminate substrate to provide a laminate member; and
at least partially cutting the laminate member to provide the piezoelectric vibrators in the form of teeth of comb.
The present disclosure relates to the subject matter contained in Japanese patent application Nos. Hei. 11-371155 (filed on Dec. 27, 1999), 2000-17886 (filed on Jan. 24, 2000), and, which are expressly incorporated herein by reference in their entireties.